Strand-wound bladder

ABSTRACT

An article of footwear or another product may incorporate a pressure chamber that includes (a) a bladder at least partially formed from a polymer material that is sealed to enclose a pressurized fluid and (b) a strand wound around the bladder and secured to the bladder. In manufacturing the pressure chamber, a bladder with an elongate configuration may be formed. A strand is wound around the bladder, and the strand is secured to the bladder. When incorporated to a sole structure of the article of footwear, for example, a portion of the bladder that includes the strands may be exposed at an outer surface of the sole structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. application Ser. No. 12/938,217,titled “Strand-Wound Bladder” and filed Nov. 2, 2010, which applicationis incorporated by reference herein.

BACKGROUND

Conventional articles of athletic footwear include two primary elements,an upper and a sole structure. The upper is generally formed from aplurality of elements (e.g., textiles, foam, leather, synthetic leather)that are stitched or adhesively bonded together to form an interior voidfor securely and comfortably receiving a foot. The sole structureincorporates multiple layers that are conventionally referred to as asockliner, a midsole, and an outsole. The sockliner is a thin,compressible member located within the void of the upper and adjacent toa plantar (i.e., lower) surface of the foot to enhance comfort. Themidsole is secured to the upper and forms a middle layer of the solestructure that attenuates ground reaction forces during walking,running, or other ambulatory activities. The outsole forms aground-contacting element of the footwear and is usually fashioned froma durable and wear-resistant rubber material that includes texturing toimpart traction.

The primary material forming many conventional midsoles is a polymerfoam, such as polyurethane or ethylvinylacetate. In some articles offootwear, the midsole may also incorporate a fluid-filled chamber thatincreases durability of the footwear and enhances ground reaction forceattenuation of the sole structure. In some footwear configurations, thefluid-filled chamber may be at least partially encapsulated within thepolymer foam, as in U.S. Pat. No. 5,755,001 to Potter, et al., U.S. Pat.No. 6,837,951 to Rapaport, and U.S. Pat. No. 7,132,032 to Tawney, et al.In other footwear configurations, the fluid-filled chamber maysubstantially replace the polymer foam, as in U.S. Pat. No. 7,086,180 toDojan, et al. In general, the fluid-filled chambers are formed from anelastomeric polymer material that is sealed and pressurized, but mayalso be substantially unpressurized or pressurized by an externalsource. In some configurations, textile or foam tensile members may belocated within the chamber, or reinforcing structures may be bonded toan exterior surface of the chamber to impart shape to or retain anintended shape of the chamber.

Fluid-filled chambers suitable for footwear applications may bemanufactured by a two-film technique, in which two separate sheets ofelastomeric film are bonded together to form a peripheral bond on theexterior of the chamber and to form a generally sealed structure. Thesheets are also bonded together at predetermined interior areas to givethe chamber a desired configuration. That is, interior bonds (i.e.,bonds spaced inward from the peripheral bond) provide the chamber with apredetermined shape and size upon pressurization. In order to pressurizethe chamber, a nozzle or needle connected to a fluid pressure source isinserted into a fill inlet formed in the chamber. Followingpressurization of the chamber, the fill inlet is sealed and the nozzleis removed. A similar procedure, referred to as thermoforming, may alsobe utilized, in which a heated mold forms or otherwise shapes the sheetsof elastomeric film during the manufacturing process.

Chambers may also be manufactured by a blowmolding technique, wherein amolten or otherwise softened elastomeric material in the shape of a tubeis placed in a mold having the desired overall shape and configurationof the chamber. The mold has an opening at one location through whichpressurized air is provided. The pressurized air induces the liquefiedelastomeric material to conform to the shape of the inner surfaces ofthe mold. The elastomeric material then cools, thereby forming a chamberwith the desired shape and configuration. As with the two-filmtechnique, a nozzle or needle connected to a fluid pressure source isinserted into a fill inlet formed in the chamber in order to pressurizethe chamber. Following pressurization of the chamber, the fill inlet issealed and the nozzle is removed.

SUMMARY

Various features of a pressure chamber, which may be incorporated intoarticles of footwear and other products, are disclosed below. Thepressure chamber includes a bladder at least partially formed from apolymer material that is sealed to enclose a pressurized fluid.Additionally, the pressure chamber includes a strand wound entirelyaround the bladder and secured to the bladder.

A method of manufacturing a pressure chamber is also disclosed below.The method includes forming a bladder with an elongate configuration. Astrand is wound around the bladder, and the strand is secured to thebladder. Additionally, the bladder may be incorporated into a solestructure of an article of footwear, and at least a portion of thebladder that includes the strand is exposed at an outer surface of thesole structure.

The advantages and features of novelty characterizing aspects of theinvention are pointed out with particularity in the appended claims. Togain an improved understanding of the advantages and features ofnovelty, however, reference may be made to the following descriptivematter and accompanying figures that describe and illustrate variousconfigurations and concepts related to the invention.

FIGURE DESCRIPTIONS

The foregoing Summary and the following Detailed Description will bebetter understood when read in conjunction with the accompanyingfigures.

FIG. 1 is a lateral side elevational view of an article of footwear.

FIG. 2 is a medial side elevational view of the article of footwear.

FIGS. 3A and 3B are cross-sectional views of the article of footwear, asdefined by section lines 3A and 3B in FIG. 1.

FIG. 4 is a perspective view of a pressure chamber from the article offootwear.

FIG. 5 is a top plan view of the pressure chamber.

FIGS. 6A and 6B are cross-sectional views of the pressure chamber, asrespectively defined by section lines 6A and 6B in FIG. 5.

FIGS. 7A-7O are top plan views corresponding with FIG. 5 and depictingfurther configurations of the pressure chamber.

FIGS. 8A-8D are cross-sectional views corresponding with a portion ofFIG. 6A and depicting further configurations of the pressure chamber.

FIGS. 9A-9C are exploded perspective views depicting furtherconfigurations of the pressure chamber.

FIG. 10 is a top plan view of another configuration of the pressurechamber.

FIG. 11 is a side elevational view of the pressure chamber depicted inFIG. 10.

FIG. 12 is a top plan view of yet another configuration of the pressurechamber.

FIG. 13 is a side elevational view of the pressure chamber depicted inFIG. 12.

FIG. 14 is a side elevational view of another configuration of thearticle of footwear.

FIG. 15 is a cross-sectional view of the article of footwear, as definedby section line 15 in FIG. 14.

FIG. 16 is a side elevational view of yet another configuration of thearticle of footwear.

FIG. 17 is a cross-sectional view of the article of footwear, as definedby section line 17 in FIG. 16.

FIGS. 18A-18F are schematic side elevational views of a process formanufacturing the pressure chamber.

DETAILED DESCRIPTION

The following discussion and accompanying figures disclose variousconfigurations of pressure chambers, which have the structures ofstrand-wound bladders. Concepts related to the pressure chambers aredisclosed with reference to an article of footwear having aconfiguration that is suitable for running. However, the pressurechambers are not limited to footwear designed for running, and may beutilized with a wide range of athletic footwear styles, includingbaseball shoes, basketball shoes, cross-training shoes, football shoes,golf shoes, soccer shoes, tennis shoes, and walking shoes, for example.The pressure chambers may also be utilized with footwear styles that aregenerally considered to be non-athletic, including dress shoes, loafers,sandals, and boots. The concepts disclosed herein may apply, therefore,to a wide variety of footwear styles. In addition to footwear, conceptsassociated with the pressure chambers may also be applied to a varietyof other products.

General Footwear Structure

An article of footwear 10 is depicted in FIGS. 1 and 2 as including anupper 20 and a sole structure 30. For reference purposes, footwear 10may be divided into three general regions: a forefoot region 11, amidfoot region 12, and a heel region 13, as shown in FIGS. 1 and 2.Footwear 10 also includes a lateral side 14 and a medial side 15.Forefoot region 11 generally includes portions of footwear 10corresponding with the toes and the joints connecting the metatarsalswith the phalanges. Midfoot region 12 generally includes portions offootwear 10 corresponding with the arch area of the foot, and heelregion 13 corresponds with rear portions of the foot, including thecalcaneus bone. Lateral side 14 and medial side 15 extend through eachof regions 11-13 and correspond with opposite sides of footwear 10.Regions 11-13 and sides 14-15 are not intended to demarcate preciseareas of footwear 10. Rather, regions 11-13 and sides 14-15 are intendedto represent general areas of footwear 10 to aid in the followingdiscussion. In addition to footwear 10, regions 11-13 and sides 14-15may also be applied to upper 20, sole structure 30, and individualelements thereof.

Upper 20 is depicted as having a substantially conventionalconfiguration incorporating a plurality of material elements (e.g.,textiles, foam, leather, and synthetic leather) that are stitched oradhesively bonded together to form an interior void for securely andcomfortably receiving a foot. The various material elements may impartproperties of air-permeability, compressibility, durability,flexibility, water-resistance, and wear-resistance, for example. Anankle opening 21 in heel region 13 provides access to the interior void.In addition, upper 20 may include a lace 22 that is utilized in aconventional manner to modify the dimensions of the interior void,thereby securing the foot within the interior void and facilitatingentry of the foot into and removal of the foot from the interior void.Lace 22 may extend through apertures in upper 20, and a tongue portionof upper 20 may extend between the interior void and lace 22. Given thatvarious aspects of the present invention primarily relate to solestructure 30, upper 20 may exhibit the general configuration discussedabove or the general configuration of practically any other conventionalor non-conventional upper. Accordingly, the structure of upper 20 mayvary significantly.

Sole structure 30 is secured to upper 20 and has a configuration thatextends between upper 20 and the ground. The primary elements of solestructure 30 are a midsole 31 and an outsole 32. Midsole 31 may beformed from a polymer foam material, such as polyurethane orethylvinylacetate, that encapsulates a pair of pressure chambers 40 thatenhance the cushioning (i.e., ground reaction force attenuation)characteristics of sole structure 30. Midsole 31 may also incorporateone or more moderators, plates, or reinforcing structures, for example,that further enhance the cushioning characteristics of sole structure 30or the performance properties of footwear 10. Outsole 32, which may beabsent in some configurations of footwear 10, is secured to a lowersurface of midsole 31 and may be formed from a rubber material thatprovides a durable and wear-resistant surface for engaging the ground.Outsole 32 may also be textured to enhance the traction (i.e., friction)properties between footwear 10 and the ground. In addition, solestructure 30 incorporates a sockliner 33 that is located with in thevoid in upper 20 and adjacent a plantar (i.e., lower) surface of thefoot to enhance the comfort of footwear 10.

Pressure chambers 40 are at least partially embedded within midsole 31and are generally positioned below upper 20 and above outsole 32. Eachof pressure chambers 40 is located in heel region 13 and on one oflateral side 14 and medial side 15. Moreover, portions of pressurechambers 40 may be exposed on each of lateral side 14 and medial side15. In addition to enhancing the aesthetic properties of footwear 10,exposing pressure chambers 40 locates pressure chambers 40 at theperiphery of midsole 31, which has an effect upon the cushioningcharacteristics and stability of sole structure 30. As described ingreater detail below, the configurations, the quantity, and thelocations of pressure chambers 40 may vary significantly within footwear10.

Pressure Chamber Configuration

One of pressure chambers 40 is depicted individually in FIGS. 4-6B asincluding a bladder 41 and one or more strands 42. Bladder 41 has agenerally hollow structure that encloses a pressurized fluid, andstrands 42 extend around bladder 41. A material forming strands 42 mayhave greater tensile strength or greater stretch-resistance than amaterial forming bladder 41. An advantage of this configuration is thatstrands 42 may form a tensile restraining structure that limits theamount by which bladder 41 stretches, distends, or otherwise expands dueto the pressurized fluid within bladder 41. That is, strands 42 maylimit the expansion of bladder 41 when pressurized.

Bladder 41 is formed from a polymer material that provides a sealedouter barrier for enclosing the pressurized fluid. Although the shape ofbladder 41 may vary significantly, bladder 41 is depicted as having anelongate and substantially cylindrical configuration that includes afirst end region 51, a second end region 52, and a center region 53. Theform and shape of bladder 41 suggest a longitudinal axis 54 essentiallyextending from first end region 51 to second end region 52 and passingthrough central region 53. Additionally, bladder 41 includes aperipheral bond 55 where polymer sheets or a parison are bonded to eachother during a manufacturing process for bladder 41.

In some configurations, bladder 41 is formed such that longitudinal axis54 follows an arbitrary three-dimensional contour. For example,longitudinal axis 54 may be formed to be curved, contoured, or tapered.Longitudinal axis 54 may also follow a contour substantially conformingto lateral side 14, medial side 15, a portion of a foot, or a shapedesirable for a foot to rest upon or against in an article of footwear.Moreover, the contour may be desirable to provide arch support, forexample, or to raise the heel of the foot in relation to the toes. Aswith many pressure vessels and other structures that contain pressurizedfluids, the elongate and cylindrical configuration of bladder 41provides a suitable shape for enclosing the pressurized fluid withinbladder 41. As such, many configurations of bladder 41 have an elongateshape in which a length of chamber 44 exceeds a diameter (or a width anda height) of chamber 44 by a factor of three or more.

In addition to overall variations in the shape of bladder 41, theconfigurations of end regions 51 and 52 may also vary to be rounded,blunt, or protruding. As examples, end regions 51 and 52 may be formedto exhibit a tapered configuration, or end regions 51 and 52 may beformed to bulge outward from center region 53 along longitudinal axis 54even when bladder 41 is essentially unpressurized (i.e., inflated to thepressure or air surrounding pressure chamber 40). Alternatively, endregions 51 and 52 may be snub-nosed or blunt. That is, end regions 51and 52 may be formed to be substantially planar and circular and to notappreciably bulge outward from center region 53 along longitudinal axis54 when bladder 41 is essentially unpressurized.

A wide range of polymer materials that are suitable for containingfluids, particularly when pressurized, may be utilized to form bladder41. In selecting a polymer material for bladder 41, engineeringproperties of the material (e.g., tensile strength, stretch properties,and fatigue characteristics) may be considered. Examples of polymermaterials that may be suitable for bladder 41 include thermoplasticpolyurethane, polyester, polyester polyurethane, and polyetherpolyurethane. Bladder 41 may also be formed from a material thatincludes alternating layers of thermoplastic polyurethane andethylene-vinyl alcohol copolymer, as disclosed in U.S. Pat. Nos.5,713,141 and 5,952,065 to Mitchell, et al. Another suitable materialfor bladder 41 is a flexible microlayer membrane that includesalternating layers of a gas barrier material and an elastomericmaterial, as disclosed in U.S. Pat. Nos. 6,082,025 and 6,127,026 toBonk, et al. Additional suitable materials are disclosed in U.S. Pat.Nos. 4,183,156 and 4,219,945 to Rudy. Further suitable materials includethermoplastic films containing a crystalline material, as disclosed inU.S. Pat. Nos. 4,936,029 and 5,042,176 to Rudy, and polyurethaneincluding a polyester polyol, as disclosed in U.S. Pat. Nos. 6,013,340;6,203,868; and 6,321,465 to Bonk, et al.

A variety of fluids may be enclosed within bladder 41, including bothgasses and liquids. In some configurations, gel materials may also beenclosed within bladder 41. With regard to gasses, bladder 41 mayenclose air, nitrogen, octafluorapropane, or any of the gasses disclosedin U.S. Pat. No. 4,340,626 to Rudy, such as hexafluoroethane and sulfurhexafluoride. As an example, the fluid within bladder 41 may bepressurized between zero and seven hundred kilopascals (i.e.,approximately one hundred one pounds per square inch) or more.

Strand 42 extends around bladder 41 to form a tensile restrainingstructure that limits the expansion of bladder 41 when pressurized. Asan example of the manner in which strand 42 may be wound around bladder41, FIGS. 4 and 5 depict a configuration wherein four segments ofstrands 42 are wound around bladder 41, thereby forming a network ofcrossed strands 42 that extend over the outer surface of bladder 41.More particularly, the four segments of strand 42 are wound aroundbladder 41 in a helical configuration. That is, each segment of strands42 extends around longitudinal axis 54 and along the length oflongitudinal axis 54, thereby extending from first end region 51 tosecond end region 52. Moreover, two segments of strands 42 are woundaround longitudinal axis 54 from first end region 51 to second endregion 52 in a clockwise manner, and two other segments of strands 42are wound around longitudinal axis 54 from first end region 51 to secondend region 52 in a counter-clockwise manner. This configurationeffectively forms a mesh or net structure that extends over bladder 41.As discussed in greater detail below, however, the manner in whichstrands 42 extend around bladder 41 may vary significantly.

Strands 42 may be formed from any generally one-dimensional material. Asutilized with respect to the present invention, the term“one-dimensional material” or variants thereof is intended to encompassgenerally elongate materials exhibiting a length that is substantiallygreater than a width and a thickness. Accordingly, suitableconfigurations for strands 42 include various filaments, fibers, yarns,threads, and cables that are formed from one or more of rayon, nylon,polyester, polyacrylic, silk, cotton, carbon, glass, aramids (e.g.,para-aramid fibers and meta-aramid fibers), ultra high molecular weightpolyethylene, liquid crystal polymer, and various metals. Althoughone-dimensional materials will often have a cross-section where widthand thickness are substantially equal (e.g., a round or squarecross-section), some one-dimensional materials may have a width that isgreater than a thickness (e.g., a rectangular, oval, or otherwiseelongate cross-section). Despite the greater width, a material may beconsidered one-dimensional if a length of the material is substantiallygreater than a width and a thickness of the material.

An advantage of locating strands 42 around bladder 41 relates to theexpansion of bladder 41 when pressurized. If strands 42 are not woundaround bladder 41 when bladder 41 is pressurized, bladder 41 maystretch, distend, or otherwise expand outward in center region 53. Incontrast, if strands 42 are wound around bladder 41 when bladder 41 ispressurized, the tension in strands 42 may allow bladder 41 to expandoutward by a comparatively lesser amount. Accordingly, strands 42 form atensile restraining structure that limits the expansion of bladder 41when pressurized.

Although strands 42 may lie against an outer surface of bladder 41,strands 42 are generally secured to bladder 41. Although adhesives orother methods of securing may be used, a polymer bond may secure bladder41 and strands 42 to each other. As utilized herein, the term “polymerbond” or variants thereof is defined as a securing technique betweenbladder 41 and strands 42 that involves a softening or melting of apolymer material within at least one of bladder 41 and strands 42 suchthat bladder 41 and strands 42 are secured to each other when cooled. Asexamples, polymer bonding may involve (a) the melting or softening ofpolymer materials within each of bladder 41 and strands 42 such that thepolymer materials intermingle with each other (e.g., diffuse across aboundary layer between the polymer materials) and are secured togetherwhen cooled; (b) the melting or softening of a polymer material withinbladder 41 such that the polymer material extends into or infiltratesthe structure of strands 42 (e.g., extends around or bonds withfilaments or fibers in strands 42) to secure bladder 41 and strands 42together when cooled; and (c) the melting or softening of a polymermaterial within one of bladder 41 and strands 42 such that the polymermaterial extends into or infiltrates crevices or cavities to secure theelements together when cooled.

Polymer bonding may occur when only one element of pressure chamber 40(i.e., one of bladder 41 or strands 42) includes a polymer material orwhen both elements of pressure chamber 40 (i.e., both bladder 41 andstrands 42) include polymer materials. Additionally, polymer bondingdoes not generally involve the use of adhesives or other securingmethods or devices, but involves directly bonding elements to each otherwith heat or a combination of heat and pressure. In some situations,however, adhesives or other securing methods or devices may be utilizedto supplement the polymer bond or the joining of elements throughpolymer bonding.

In configurations where bladder 41 and strands 42 include the samepolymer material, the polymer bond may include the commingling andmerging of the commonly-shared polymer material of bladder 41 and thecommonly-shared polymer material of strands 42 to form a substantiallycontinuous combined structure. Where bladder 41 and strands 42 includedifferent polymer materials, the polymer bond may include one of eithera polymer material of bladder 41 or a polymer material of strands 42substantially conforming at the microscopic level to the specificstructure of the other polymer, including microscopic imperfections suchas pits and protrusions in the other polymer's surface. Polymer bondingmay also include a polymer material of bladder 41 extending aroundfilaments or fibers that form strands 42, thereby substantiallysurrounding individual elements within strands 42. For example, thepolymer material of bladder 41 may substantially surround the filamentsor fibers that form strands 42 at one or more places where bladder 41and strands 42 make contact.

Based upon the above discussion, pressure chamber 40 is formed from bothbladder 41 and strands 42. Bladder 41 is at least partially formed froma polymer material that encloses a pressurized fluid, and strand 42 iswound around the bladder and secured to the bladder. In thisconfiguration, strands 42 form a tensile restraining structure thatlimits the amount by which bladder 41 stretches, distends, or otherwiseexpands due to the pressurized fluid within bladder 41. Although theconfiguration disclosed above provides a suitable configuration forpressure chamber 40, a variety of other configurations are describedbelow in order to illustrate some potential variations for pressurechamber 40.

Further Pressure Chamber Configurations

Aspects of bladder 41 and strand 42 may vary significantly, dependingupon the desired properties of pressure chamber 40 or the intended usefor pressure chamber 40. Moreover, changes to the dimensions, shapes,and materials utilized within bladder 41 and strand 42 may vary theoverall properties of pressure chamber 40. That is, by changing thedimensions, shapes, and materials utilized within bladder 41 and strand42, the compressibility, impact force attenuation, flexibility, andoverall mass of pressure chamber 40 may be tailored to specific purposesor types of footwear or other products. A plurality of variations forpressure chamber 40 are discussed below. Any of these variations, aswell as combinations of these variations, may be utilized to tailor theproperties of pressure chamber 40 to an intended use or particularproduct.

The configuration of pressure chamber 40 disclosed above provides anexample of the manner in which bladder 41 may be configured and strands42 may be arranged. As a comparison, FIG. 7A discloses a configurationof pressure chamber 40 wherein strands 42 are positioned closer togetherthan in FIGS. 3-6B. Similarly, FIG. 7B discloses a configuration whereinstrands 42 are positioned further apart. Depending upon the pressure ofthe fluid within bladder 41, the specific material utilized for bladder41, the thickness of the material forming bladder 41, and theapplication in which pressure chamber 40 may be utilized, for example,the spacing of strands 42 may vary to restrain the expansion of bladder41.

A variety of other configurations for strands 42 may also restrain theexpansion of bladder 41. Referring to FIG. 7C, a majority of strands 42are oriented to extend around bladder 41 in one direction, whereas alesser number of strands 42 extend around bladder 41 in an oppositedirection. The strands 42 extending around bladder 41 in the oppositedirection may also be limited to one area of bladder 41, as depicted inFIG. 7D. Although strands 42 may extend around bladder 41 in both aclockwise and counter-clockwise direction, a single strand 42 may extendaround bladder 41 in a single direction, as depicted in FIG. 7E. As withother configurations, the spacing of the single strand 42 may vary, asdepicted in FIG. 7F. Additionally, two strands 42 may extend aroundbladder 41 in a common direction, as depicted in FIG. 7G.

In the configurations disclosed above, strands 42 extend around bladder41 in a generally helical configuration, thereby extending about thelength of longitudinal axis 54. Referring to FIG. 7H, strands 42 extendaround limited areas of bladder 41, thereby extending about a relativelysmall portion of longitudinal axis 54 or one point along longitudinalaxis 54. In order to cover other areas of bladder 41, one or more ofstrands 42 may also exhibit the generally helical configuration, asdepicted in FIG. 7I.

Pressure chamber 40 may have the generally straight or linearconfiguration disclosed above. In further configurations, however,pressure chamber 40 bladder 41 may be curved or contoured. Referring toFIG. 7J, pressure chamber 40 has a generally U-shaped structure thatmay, for example, be usable within heel region 13 of footwear 10. Moreparticularly, one side of pressure chamber 40 may extend along lateralside 14, the opposite side of pressure chamber 40 may extend alongmedial side 15, and the curved portion may extend around a back of heelregion 13. In further configurations, pressure chamber 40 may have aC-shaped or V-shaped configuration, or pressure chamber 40 may exhibitundulating N-shaped, M-shaped, or S-shaped configurations. Although allof pressure chamber 40 or bladder 41 may have an elongate configuration,portions of bladder 41 may also exhibit other configurations. Referringto FIG. 7K, for example, a central area of pressure chamber 40 may haveincreased thickness. Additionally, FIG. 7L discloses a configurationwherein strands 42 extend around various lobes of bladder 41 that extendoutward from a central area.

Polymer bonds may be solely utilized to secure strands 42 to bladder 41.In other configurations, other techniques or devices may be utilized tostrands 42 to bladder 41, or a combination of polymer bonds and theother techniques or devices may be utilized to secure strands 42 tobladder 41. Referring to FIG. 7M, strands 42 may be secured to bladder41 with a cover layer 43 that extends over strands 42. As an example,cover layer 43 may be a layer of polymer that bonds with bladder 41,thereby trapping strands 42 between bladder 41 and cover layer 43. Coverlayer may also extend across multiple segments of strands 42, asdepicted in FIG. 7N. In addition to securing strands 42 to bladder 41,cover layer 43 may also protect strands 42.

Bladder 41 is generally sealed to enclose the pressurized fluid withinpressure chamber 40. In some configurations, as depicted in FIG. 7O, avalve 56 may be coupled with bladder 41 to allow the pressure of thefluid within chamber 41 to be varied. An advantage of this configurationis that the pressure of the fluid within each of pressure chambers 40may be adjusted to the preferences, weight, or running style of anindividual wearing footwear 10.

The position of strands 42 relative to the outer surface of bladder 41may vary significantly. Referring to FIGS. 6A and 6B, strands 42 arepositioned to lie against the outer surface of bladder 41 when securedwith the polymer bond. As noted above, polymer bonding may involvedirectly bonding elements to each other with heat or a combination ofheat and pressure. Given that portions of bladder 41 may melt or softenas a result of the heat, strands 42 may become partially recessed intothe outer surface of bladder 41, as depicted in FIG. 8A, or strands 42may be fully recessed into bladder 41, as depicted in FIG. 8B. Strands42 may also be positioned adjacent to an interior surface of bladder 41,as depicted in FIG. 8C, or strands may have non-circular configurations,as depicted in FIG. 8D.

With reference to FIG. 9A, strands 42 may be secured to or bonded toeach other and may form a sheath 44 surrounding bladder 41. Withreference to FIG. 9B, in other configurations, strands 42 may beembedded in a separate sheet or tube (e.g., a textile) 45 encasingbladder 41, which may include a polymer material and may form a polymerbond with bladder 41, strands 42, or both. With reference to FIG. 9C,strands 42 may be positioned within indentations 57 in the outer surfaceof bladder 41, which may guide strands 42 into a desired configurationon the outer surface of bladder 41.

As depicted in FIGS. 1-6B, strands 42 are generally secured to bladder41. However, in other configurations, strands 42 may be unsecured tobladder 41. For example, strands 42 may lie against a surface of bladder41 in a manner that permits adjustment of a degree of tension applied tostrands 42, for example by a tightening of strands 42 about bladder 41.Furthermore, in some configurations, a sheath substantially surroundingsome portion or portions of strands 42 and may be secured (such as by apolymer bond) to bladder 41. Strands 42 may in turn be unsecured to suchsheaths, and may freely move within them, thereby facilitating thetightening of strands 42 about bladder 41. In some configurations,footwear lacing systems similar to those disclosed in U.S. Pat. Nos.6,289,558 and 7,591,050 to Hammerslag may be adapted to tighten strands42 about bladder 41.

A configuration of pressure chamber 40 that has a general shape of afoot is disclosed in FIGS. 10 and 11. When incorporated into footwear10, for example, this configuration of pressure chamber 40 may extendunder substantially all of the foot. Although pressure chamber 40 may belocated within midsole 31, this configuration of pressure chamber 40 mayalso be used as a sockliner within upper 20. In order to form relativelyflat upper and lower surfaces, pressure chamber 40 may incorporate atensile member, as disclosed in U.S. Pat. No. 6,837,951 to Rapaport,which is incorporated herein by reference. Although the tensile memberforms relatively flat upper and lower surfaces, the tensile member isgenerally unsecured to a periphery or sidewall area, which may expand atrelatively high fluid pressures. Accordingly, strands 42 may extendaround bladder 41 to prevent expansion of the periphery or sidewallarea. A similar configuration is depicted in FIGS. 12 and 13, whereinstrands 42 are present in the periphery or sidewall area, but are absentfrom portions of the upper and lower surfaces.

Further Footwear Configurations

The configuration of pressure footwear 10 disclosed above provides anexample of the manner in which pressure chamber 40 may be incorporatedinto midsole 31. In some configurations of footwear 10, pressure chamber40 may have an upper portion facing upper 20, a lower portion facingoutsole 32, and sidewall surfaces between the upper and lower portions.In such configurations, a gap at a side surface of sole structure 30 mayexpose a portion of the sidewall surfaces of pressure chamber 40including portions or segments of strands 42 wound around pressurechamber 40, and the exposed portions or segments of strands 42 mayextend from the upper portion of pressure chamber 40 to the lowerportion of pressure chamber 40 and may be secured to the sidewallportion of pressure chamber 40. Alternatively, a gap in a differentouter surface of sole structure 30 may expose other portions of pressurechamber 40 and other segments of strands 42. For example, a gap in anupper surface or a lower surface of sole structure 30 may expose a partof the upper portion of pressure chamber 40 or a part of the lowerportion of pressure chamber 40, including portions or segments ofstrands 42 wound around pressure chamber 40.

In the configuration of footwear 10 disclosed above, a gap at a sidesurface of sole structure 30 exposes portions of pressure chamber 40 inheel region 13 of midsole 31. In configurations where pressure chamber40 extends from forefoot region 11 to heel region 13, as depicted inFIGS. 14 and 15, a gap at the side surface of sole structure 30 mayexpose substantially all of the length of pressure chamber 40. However,in other configurations, a plurality of gaps in a side surface of solestructure 30 may expose pressure chamber 40. In addition, where pressurechamber 40 extends from heel region 13 to midfoot region 12 or forefootregion 11, one or more gaps at a side surface of sole structure 30 mayexpose pressure chamber 40 along any portion of midsole 31. For example,with reference to FIGS. 16 and 17, pressure chamber 40 may extendthrough heel region 13, midfoot region 12, and forefoot region 11 ofmidsole 31, and one or more gaps may expose pressure chamber 40 alongany portion or portions of the length of midsole 31, including a fulllength of midsole 31. However, in other configurations, the sidesurfaces of sole structure 30 may have no gaps exposing pressure chamber40.

Returning to FIGS. 1-3B, lateral side 14 of midsole 31 includes alateral-side pressure chamber 40, and medial side 15 of midsole 31includes a medial-side pressure chamber 40. In other configurations, asingle elongate U-shaped pressure chamber 40, as disclosed in FIGS. 7Jand 7K, may be located on both lateral side 14 and medial side 15 ofmidsole 31. In such configurations, the U-shaped pressure chamber 40 mayextend through heel region 13 on each of lateral side 14 and medial side15, and may extend at least into midfoot region 12, or through midfootregion 12 and into forefoot region 11, on lateral side 14 of midsole 31,medial side 15 of midsole 31, or both.

Additionally, pressure chambers similar to pressure chamber 40 may beincorporated into products other than articles of footwear. Equipmentframe elements similar to pressure chamber 40 may be incorporated intosporting equipment, such as various bats (e.g., baseball, softball, orcricket bats), clubs (e.g., golf clubs), mallets (e.g., polo mallets),racquets (e.g., tennis or squash racquets), and sticks (e.g., hockey orlacrosse sticks). Padding elements similar to pressure chamber 40 may beincorporated into padding or safety equipment, such as padded equipmentused in sporting uniforms (e.g., baseball, football, or hockey uniforms)and apparel worn for safety purposes (e.g., boots, harnesses, or suits).Comfort-providing elements similar to pressure chamber 40 may beincorporated into parts of bags and body-supporting articles, such ascarrying straps (e.g., golf bag or backpack straps), seat cushions, andmats (e.g., mattresses or yoga mats).

Manufacturing Methods

FIGS. 18A-18F depict aspects of an exemplary method of manufacturingpressure chamber 40. Referring to FIG. 18A, a substantially hollow andelongate bladder 41 is formed to include a fill inlet 61 through whichbladder 41 may be pressurized. A variety of molding processes may besuitable for forming bladder 41, including blowmolding, rotationalmolding, two-film techniques, or thermoforming. With reference to FIG.18B, a fluid pressurization source 62 may be connected to fill inlet 61,and bladder 41 may be pressurized to a first pressure through fill inlet61. In some manufacturing methods, the connection of fluidpressurization source 62 to fill inlet 61 and the pressurizing ofbladder 41 to a first pressure may be performed during the formation ofbladder 41.

Once bladder 41 has been pressurized to the first pressure, strands 42may be wound around bladder 41, as depicted in the series of FIGS.18C-18E. When uninflated to the first pressure, the polymer materialforming bladder 41 may collapse when wound with strands 42. By inflatingbladder 41 to the first pressure, however, the fluid within bladder 41may not collapse when wound with strands 42. In configurations wherebladder 41 has sufficient structure to resist collapsing when wound withstrands 42, the step of inflating bladder 41 to the first pressure maybe removed from the manufacturing method.

In the process of winding strands 42 around bladder 41, strands 42 mayunspool from a bobbin 63, and bladder 41 may rotate about itslongitudinal axis 54 relative to the position of bobbin 63. In thismethod, bobbin 63 may be in a substantially fixed position, and bladder41 may be substantially rotating around its longitudinal axis 54.However, other arrangements may be suitable to wind strands 42 aroundbladder 41. For example, in some manufacturing methods, bladder 41 maybe substantially static, and bobbin 63 may be substantially rotatingaround about the longitudinal axis 54 of bladder 41. In othermanufacturing methods, both bobbin 63 and bladder 41 may besubstantially rotating about longitudinal axis 54, such that thecombined effect of both rotations is that bladder 41 is effectivelyrotating about its longitudinal axis 54 relative to the position ofbobbin 63.

In the process of winding strands 42 around bladder 41, bobbin 63 mayalso move along bobbin path 64, located away from but substantiallyparallel to longitudinal axis 54. Relative to end regions 51 and 52,bobbin 63 may move either from first end region 51 to second end region52, or bobbin 63 may move from second end region 52 to first end region51 along bobbin path 64. It will be understood that other positionalrelationships may exist between the first side and the second side. Forexample, first end region 51 could be above, to the right of, or belowsecond end region 52.

Additionally, other arrangements may be suitable to wind strands 42around bladder 41. For example, in some manufacturing methods, bobbin 63may be in a substantially fixed position, and bladder 41 may move eitherfrom right to left or from left to right along its own longitudinal axis54. In other manufacturing methods, bobbin 63 may move along bobbin path64 in a first direction and bladder 41 may move along its ownlongitudinal axis 54 in a second direction, and the combined effect ofboth movements is that bobbin 63 is effectively moving from either fromleft to right or from right to left along bobbin path 64.

In the first exemplary manufacturing method, longitudinal axis 54 andbobbin path 64 are both substantially straight and parallel to eachother and define a plane that divides the space in which themanufacturing apparatus lies into a first space on one side of the planeand a second space on the other side of the plane. In the firstexemplary manufacturing method, the first space is above the plane, andthe second space is below the plane. It will be understood that otherpositional relationships may exist between the first space and thesecond space. For example, the first space could be to the right of,below, or to the left of the second space.

As bladder 41 rotates about longitudinal axis 54 relative to theposition of bobbin 64, the point of contact with unspooling strand 45may be either in the first space or in the second space. In the firstexemplary manufacturing method, the outer surface of bladder 41 mayrotate away from bobbin 64 at the point of contact. However, in othermanufacturing methods, the outer surface of bladder 41 may rotate towardbobbin 64 at the point of contact.

As bladder 41 substantially rotates about its longitudinal axis 54relative to the position of bobbin 63, and as bobbin 63 moves alongbobbin path 64, the generally helical configuration may be imparted to awinding of strands 42 around bladder 41. The direction of the impartedhelical configuration (i.e., clockwise or counter-clockwise) isinfluenced by whether the point of contact with unspooling strands 42(at which the outer surface of bladder 41 is rotating away from bobbin63) is in the first space or in the second space. The direction of theimparted helical configuration is also influenced by whether bobbin 63is moving from the first side of bobbin path 64 to the second side ofbobbin path 64, or from the second side of bobbin path 64 to first sideof bobbin path 64.

Four combinations of the two factors just described are possible. Twosuch combinations may result in a winding of a first helical handedness,while the other two may result in a winding of a second helicalhandedness opposite the first. For example, in the first exemplarymanufacturing method, strands 42 may be wound around bladder 41 in afirst winding, in which the point of contact with unspooling strands 42(at which the outer surface of bladder 41 is rotating away from bobbin63) is above the plane, and bobbin 63 is moving from left to right.Accordingly, the first winding may be of a first helical handedness. Ina symmetrical manner, strands 42 may be wound around bladder 41 in asecond winding, in which the point of contact with unspooling strands 42(which is the point at which the outer surface of bladder 41 is rotatingaway from bobbin 63) is below the plane, and bobbin 63 is moving fromright to left. Accordingly, the second winding may also be of the firsthelical handedness.

In contrast, strands 42 may be wound around bladder 41 in a thirdwinding, in which the point of contact with unspooling strands 42 isabove the plane, and bobbin 63 is moving from right to left; and, in asymmetrical manner, strands 42 may be wound around bladder 41 in afourth winding, in which the point of contact with unspooling strands 42is below the plane, and bobbin 63 is moving from left to right.Accordingly, the third winding and the fourth winding may each have asecond helical direction opposite the first helical direction.

Once strands 42 has been wound around bladder 41, strands 42 may besecured to bladder 41. In the first exemplary manufacturing method,strands 42 are secured against bladder 41 by forming a polymer bondbetween strands 42 and bladder 41.

With reference to FIG. 18F, once strands 42 has been secured to bladder41, bladder 41 may be pressurized to a second pressure, which is greaterthan the first pressure. In the manufacturing method, after bladder 41has been formed and wound with strands 42, pressurization source 62 maybe connected to fill inlet 61, and bladder 41 may be pressurized to asecond pressure through fill inlet 61. The pressurization to a secondpressure may introduce tension in strands 42, which may allow bladder 41to be inflated to a relatively high pressure while expanding relativelylittle. In some configurations, fill inlet 61 may then be sealed toprevent fluid communication between the interior of bladder 41 and theexterior of bladder 41. In other configurations, fill inlet 61 may becoupled to a valve (e.g., valve 56) to allow fluid communication betweenthe interior of bladder 41 and the exterior of bladder 41.

FIGS. 18A-18F depict a first exemplary method of manufacturing pressurechamber 40, as depicted in FIGS. 4-6B. A person having ordinary skill inthe art will understand that these methods may be extended tomanufacture further configurations of pressure chamber 40, such as thefurther configurations described above.

The invention is disclosed above and in the accompanying figures withreference to a variety of configurations. The purpose served by thedisclosure, however, is to provide an example of the various featuresand concepts related to the invention, not to limit the scope of theinvention. One skilled in the relevant art will recognize that numerousvariations and modifications may be made to the configurations describedabove without departing from the scope of the present invention, asdefined by the appended claims.

The invention claimed is:
 1. A method of manufacturing a pressurechamber, the method comprising: molding a bladder with an elongateconfiguration and that includes a fill inlet; connecting the fill inletto a pressurization source; pressurizing a fluid within the bladder to afirst pressure through the fill inlet; after the step of connecting andthe step of pressurizing the fluid within the bladder to the firstpressure, winding a strand around the bladder while the fluid within thebladder is pressurized to the first pressure; after the step of windingthe strand around the bladder, securing the strand to the bladder, andafter the step of securing the strand to the bladder, pressurizing thefluid within the bladder to a second pressure, the second pressure beinggreater than the first pressure, and wherein the pressurized bladder hasa cylindrical configuration and the strand forms part of an exposedexterior surface of the bladder after it is pressurized to the secondpressure; and incorporating the pressure chamber into a sole structureof an article of footwear.
 2. The method recited in claim 1, wherein thestep of pressurizing the fluid within the bladder to the second pressureincludes increasing tension of the strand.
 3. The method recited inclaim 1, wherein the step of winding includes imparting a helicalconfiguration to the strand.
 4. The method recited in claim 1, whereinthe step of winding includes locating the strand about a fixed point ona longitudinal axis of the bladder.
 5. The method recited in claim 1,wherein the step of winding includes locating the strand withinindentations in an outer surface of the bladder, and the step ofsecuring includes bonding the strand to the bladder within theindentations.
 6. The method recited in claim 1, wherein the step ofsecuring includes forming a polymer bond between polymer materials ofthe bladder and the strand.
 7. The method recited in claim 1, whereinthe step of securing includes embedding the strand within a polymermaterial of the bladder.
 8. The method recited in claim 1, wherein thestep of forming includes incorporating a valve into the bladder.
 9. Amethod of manufacturing a pressure chamber, the method comprising:molding a bladder with an elongate configuration and that includes afill inlet; connecting the fill inlet to a pressurization source;pressurizing a fluid within the bladder to a first pressure through thefill inlet; after the step of connecting and the step of pressurizingthe fluid within the bladder to the first pressure, winding a strandaround the bladder while the fluid within the bladder is pressurized tothe first pressure; after the step of winding the strand around thebladder, securing the strand to the bladder; after the step of securingthe strand to the bladder, pressurizing the fluid within the bladder toa second pressure, the second pressure being greater than the firstpressure; and incorporating the pressure chamber into a sole structureof an article of footwear, wherein the strand forms part of an exposedexterior surface of the bladder after it is pressurized to the secondpressure.
 10. The method recited in claim 9, wherein the step ofincorporating the pressure chamber into the sole structure includesexposing at least a portion of the pressure chamber that includes thestrand at an outer surface of the sole structure.
 11. The method recitedin claim 9, wherein the step of winding includes imparting a helicalconfiguration to the strand.
 12. The method recited in claim 9, whereinthe step of securing includes forming a bond between the bladder and thestrand.
 13. The method recited in claim 10, wherein the step of securingincludes embedding the strand within a polymer material of the bladder.14. The method recited in claim 9, wherein the step of incorporatingincludes at least partially locating the bladder within a polymer foammaterial of the sole structure.
 15. The method recited in claim 9,wherein the step of incorporating includes locating the bladder in atleast one of a medial side region and a lateral side region of the solestructure.
 16. The method of claim 9, wherein the step of windingcomprises winding multiple strands around the bladder, and wherein thestep of securing comprises securing the multiple strands to the bladder.17. The method of claim 16, wherein winding multiple strands around thebladder comprises winding a first strand around the bladder with a firsthelical configuration and winding a second strand around the bladderwith a second helical configuration different from the first helicalconfiguration.
 18. The method of claim 17, wherein the first helicalconfiguration comprises winding in a clockwise direction along alongitudinal length of the bladder and the second helical configurationcomprises winding in a counter-clockwise direction along a longitudinallength of the bladder.
 19. The method of claim 1, wherein a length ofthe pressure chamber exceeds a diameter of the pressure chamber by afactor of three or more.
 20. The method of claim 1, wherein a materialforming the strand has a tensile strength greater than a tensilestrength of a material forming the bladder.
 21. The method of claim 1,wherein the molding comprises blowmolding.